panic: hat_unload -- What's this mean

[Alexander Dupuy]

I've seen the same panic on our Sun-2/170 running 4.0.1.  "hat" stands for
hashed address table, but beyond that I couldn't say.  We have also had a
wierd panic every time we boot our 2/120s under 4.0[.1].  Just before
vmunix starts probing for devices, right after it sizes memory, we get a
"panic: hat_unlock".  After it (tries to) write a crash dump, it
(auto)boots normally.  We haven't ever seen this on our 2/170, though.
Could it be a CPU board rev problem which only our ancient 2/120s have?

@alex